JPH11270312A - Rocker arm and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rocker arm having a highly accurate valve stem guide groove, which can improve production efficiency and reduce cost. SOLUTION: One side connection is provided with a pair of both side walls 22 and one end connection wall 30 which connects between one end portions of the both side walls 22 and which is configured so that the tip of a valve stem abuts on the lower surface side. On both side regions of the wall 30, a projection process is performed from the upper surface side, and a pair of convex ridges 41 a is formed on both lower surface sides of the one end connecting wall 30 so as to protrude downward, between the pair of convex ridges. A rocker arm in which a valve stem guide groove 40 having the convex ridge 41a as a guide wall 41 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rocker arm for opening and closing a valve provided on a cylinder head with rotation of a cam in a valve operating mechanism of an internal combustion engine of a vehicle, and a method of manufacturing the same.

[0002]

2. Description of the Related Art FIG. 9 is a sectional view showing a valve train in an internal combustion engine of a vehicle. As shown in the figure, a cam (3) that rotates in conjunction with a crankshaft (2) is provided in the valve mechanism.
A rocker arm (1) for converting the rotational movement of the valve stem into a reciprocating linear movement of a valve stem (5) in a valve (4) such as an intake valve or an exhaust valve is provided.

As shown in FIGS. 9 and 10, the rocker arm (1) has a pair of side walls (1) arranged in parallel.
1) and one end connecting wall (12) and the other end connecting wall (13) for connecting between one end and the other end of both side walls (11). A support shaft (8) of a roller (7) is fixed to a shaft fixing hole provided in a longitudinally intermediate region of both side walls (11), and the roller (7) and the cam (3) are fixed. It is configured to be able to make rolling contact. A pivot engagement recess (13a) is formed on the lower surface side of the other end connecting wall (13) of the rocker arm (1), and the pivot portion (6) fixed to the cylinder head is formed in the recess (13a). ) Is arranged in the engaged state, and the tip of the valve stem (5) is arranged in a contact state on the lower surface of the one end connecting wall (12). In addition, one end connecting wall (12)
A valve stem guide groove (12a) is formed on the lower surface side of the valve stem, and the tip of the valve stem (5) is connected to the guide groove (12a).
a), and the tip of the valve stem is inserted into the groove wall (both side walls 1).
1 to prevent the rocker arm (1) from being displaced in the horizontal direction with the pivot (6) as a fulcrum.

[0004]

The rocker arm (1) as described above has a complicated shape, for example, a guide groove (12a) for accommodating the tip of the valve stem is provided in one end connecting wall (12). In general, it is generally manufactured by forging or precision casting (lost wax).

[0005] However, the rocker arm (1) is
When manufactured by low-efficiency machining such as forging or precision casting, there is a problem that production efficiency is reduced and costs are increased.

On the other hand, in recent years, with the increase in speed and output of an internal combustion engine, it has been desired to reduce the weight of the rocker arm in order to reduce the inertial weight. Many have been proposed.

However, since the rocker arm has a complicated shape such as the guide groove (12a), the number of steps is increased in conventional press working, and it is difficult to form the guide groove (12a) with sufficient accuracy. Thus, there is a problem that the production efficiency decreases and the cost increases.

The present invention provides a rocker arm having a high-precision valve stem guide groove and a method of manufacturing the same, which can solve the above-mentioned problems of the prior art, improve the production efficiency and reduce the cost. Aim.

[0009]

In order to achieve the above object, a rocker arm according to the first aspect of the present invention connects a pair of both side walls and one end of the both side walls, and has a valve stem tip on a lower surface side. And one end connecting wall configured to be abutted, and a pressing process is performed on both side regions of the one end connecting wall from the upper surface side, and a pair of ridges are formed on both lower side surfaces of the one end connecting wall. Is formed so as to project downward, and a valve stem guide groove is formed between the pair of convex ridges, the valve stem guide groove being formed with the convex ridge as a guide wall.

In the rocker arm according to the first aspect of the present invention, a pair of protruding ridges are formed on both sides of the lower surface of the one end connecting wall so as to protrude downward by projection press working, and between the ridges. Since the valve stem guide groove is formed with the ridge portion as a guide wall, for example, as compared with the case where the guide groove is formed using low-efficiency machining such as forging or precision casting,
The valve stem guide groove can be formed easily and accurately.

On the other hand, the second invention comprises a step of obtaining a metal plate-shaped workpiece having a predetermined shape, and performing a bending process on the plate-shaped workpiece to form a pair of both side walls and a pair of side walls. Obtaining a bent product having one end connecting wall connected to one end, and one end connecting wall configured so that the tip of the valve stem is abutted on the lower surface side. Before bending, both sides of the region corresponding to the one end connecting wall in the plate-like processed product are subjected to pressing from the upper surface side, and a pair of ridges are formed on both lower surface sides of the corresponding region. Is formed in a downwardly projecting shape, and a valve stem guide groove is formed between the pair of convex ridges with the convex ridge as a guide wall.

The method for manufacturing a rocker arm according to the second aspect of the present invention specifies one mode of the manufacturing process in the rocker arm according to the first aspect of the present invention. In the present method, particularly, at the stage of a plate-like processed product. In addition, since the guide wall is formed by the projection pressing process, the processing can be performed more easily and accurately than in the case where the pressing process is performed after the bending process.

Further, in the second invention, the plate-like processed product is bent by using the pressing groove provided on the upper surface side of the plate-shaped processed product as a bent portion to form the bent processed product. On the other hand, it is preferable to employ a configuration in which one side surface of the pressing groove is brought into close contact with the bottom surface of the pressing groove by pressing both side walls of the bent product toward the one end connecting wall side.

That is, when this configuration is adopted, sufficient rigidity can be secured at the connecting portion between the side walls and the one end connecting wall.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a rocker arm according to an embodiment of the present invention will be described in detail with reference to the drawings. In the following drawings, the rocker arm (including the intermediate processed product) is shown in a state during the manufacturing process, that is, in a state where the rocker arm is turned upside down with respect to the actual use state, but in the following description, According to the actual use condition, "upper side" of the drawing
Is described as “lower side”.

The rocker arm (20) of the present invention is shown in FIG.
As shown in the figure, a pair of opposing side walls (22)
And one end connecting wall (30) connecting between the lower ends of the two end walls (22), and the other end connecting wall (23) connecting between the lower ends of the other ends. Further, a valve stem guide groove (40) is formed on the lower surface (32) of the one end connecting wall (30) with a pair of convex ridges (41a) provided on both sides thereof in a downwardly projecting shape as guide walls (41). The pivot engagement recess (2) is formed in the center of the lower surface side of the other end connecting wall (23).
4) is formed. A shaft fixing hole (21) having an axial center coincident with each other is formed at a longitudinally intermediate portion of both side walls (22).

To manufacture the rocker arm (20), first, as shown in FIG. 1, a predetermined region of a steel plate is punched to obtain a substantially rectangular punched plate having arc-shaped convex portions on both side edges. By punching out the center of the punched plate, a blank product (20a) having a drum-shaped hole is obtained.

Next, a semi-spherical pivot engaging recess (24) is formed by overhanging in a region corresponding to the center of the lower surface of the other end connecting wall (23) in the blank processed product (20a).

Subsequently, as shown in FIGS. 2 and 5, the one end connecting wall (3) of the blank processed product (20a) is formed.
Pressing is performed on both sides of the region (30a) corresponding to (0) such that a pressing punch (not shown) is driven in from the upper surface side. As a result, both sides of the corresponding region (30a) are plastically deformed so that the material in the corresponding region moves downward, and a pair of pressing grooves (45) are formed on both upper surface sides of the corresponding region (30a).
Is formed, a pair of ridges (41a) are formed on both sides on the lower surface side of the corresponding region (30a) so as to protrude downward. Thus, between the pair of ridges (41a) on the lower surface side of the corresponding area (30a), the ridge (41a) is used as the guide wall (41), and the lower surface (32) of the corresponding area (30a) is the bottom surface (valve). A valve stem guide groove (40) serving as a stem contact surface is formed.

In this embodiment, as shown in FIG. 5, the pressing groove (45) is formed such that the opening thereof has a bottom surface (45).
Both side surfaces (45a) are formed as inclined surfaces having a predetermined angle (θ) with respect to the pressing direction line (P) so as to be larger than b). Accordingly, it is possible to prevent the pressing punch from biting the blank processed product (20a) during the pressing process, and it is possible to smoothly perform the continuous processing.

Next, as shown in FIGS. 3 and 6, the blank (20a) is folded at the corner between the outer side surface (45a) and the bottom surface (45b) of the pair of pressing grooves (45). Perform bending processing as a music line.

Thus, the lower ends of the two side walls (22) are connected by one end connecting wall (30) and the other end connecting wall (23), and between the pair of side walls (22). A U-shaped bent product (20b) having an opening for accommodating and viewing the roller is provided between the one end connecting wall (30) and the other end connecting wall (23). Needless to say, the valve stem guide groove (40) is arranged on the lower surface side of the one end connecting wall (30) in the bent product (20b), and the pivot engagement concave portion (23) is
It is arranged on the lower surface side of the other end connecting wall (23).

Next, as shown in FIG. 7, the bent product (20
The two side walls (22) at one end side of b) are pressed and formed downward, and the both side walls (22) and one end connecting wall (30) are formed.
Of the pressing groove (45) is buckled and deformed so that the side surface (45a) located outside the pressing groove (45) is in close contact with the bottom surface (45b) of the pressing groove (45). In FIG. 7, for reference, the state of both side walls (22) in the bent product (20b) before pressure forming is indicated by broken lines.

Next, as shown in FIG.
2) Punching punches are punched from both sides into a longitudinal middle portion to form shaft fixing holes (21) at predetermined positions on both side walls (22), the axes of which coincide with each other.

Thus, the manufacture of the rocker arm (20) of the present embodiment is completed.

According to the manufacturing method of this embodiment, the rocker arm (2) is formed only by pressing such as outer diameter punching, pressing, bending, pressing, and punching.
0), it is possible to improve production efficiency and reduce costs without requiring low-efficiency machining such as forging or precision casting.

Further, since the guide wall (41) is formed by pressing and projecting at the stage of the plate-shaped blank processed product (20a), compared with the case where pressing is performed after bending, for example. In addition, it is possible to easily and accurately process, improve the positional accuracy and dimensional accuracy of the guide wall (41), that is, the guide groove (40), and further improve the productivity.

In the present embodiment, both side walls (22) of the bent product (20b) are formed by pressing, and the periphery of the pressing groove (45) is deformed by buckling to form one of the pressing grooves (45). Because the side surface (45a) is in close contact with the bottom surface (45b),
Sufficient rigidity can be ensured at the connecting portion between the side walls (22) and the one-end connecting wall (30), and the rigidity of the rocker arm itself can be improved.

[0029]

As described above, according to the rocker arm of the first aspect of the present invention, a pair of protruding ridges are formed on both sides of the lower surface of the one end connecting wall so as to protrude downward by projection press working. In order to form a valve stem guide groove having the convex ridge portion as a guide wall between the convex ridge portions, for example, a case where the guide groove is formed by low-efficiency machining such as forging or precision casting is used. Since the valve stem guide groove can be formed easily and accurately as compared with the above, a guide groove having high positional accuracy and dimensional accuracy can be formed, and furthermore, the production efficiency can be improved and the cost can be reduced. There is.

On the other hand, the method for manufacturing a rocker arm according to the second aspect of the present invention specifies one mode of the manufacturing process in the rocker arm according to the first aspect of the present invention. Can be. In particular, in the present manufacturing method, since the guide wall is formed by pressing and projecting at the stage of the plate-like processed product, it is much simpler than, for example, performing pressing after bending. And can be processed accurately, guide walls,
In other words, there is an effect that the positional accuracy and the dimensional accuracy of the valve stem guide groove can be further improved, and the productivity can be further improved.

In the second invention, when one side surface of the pressing groove is brought into close contact with the bottom surface by pressing both side walls of the bent product, the connecting portion between the both side walls and one end connecting wall is formed. There is an advantage that sufficient rigidity can be secured, and thus the rigidity of the rocker arm itself can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a blank product as an intermediate product in a method of manufacturing a rocker arm according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a blank processed product after a protrusion pressing process in the manufacturing method of the embodiment.

FIG. 3 is a perspective view showing a bent product as an intermediate product in the manufacturing method of the embodiment.

FIG. 4 is a perspective view showing a rocker arm manufactured by the manufacturing method of the embodiment.

FIG. 5 is a cross-sectional view showing the blank processed product of the embodiment after a projection press process.

FIG. 6 is a sectional view showing a bent product of the embodiment.

FIG. 7 is a cross-sectional view showing the bent product of the embodiment after pressure molding.

FIG. 8 is a sectional view showing a rocker arm according to the embodiment.

FIG. 9 is a cross-sectional view showing a valve mechanism of an internal combustion engine in a conventional vehicle.

FIG. 10 is a sectional view showing a rocker arm applied to a conventional valve train.

[Explanation of symbols]

 Reference Signs List 20: Rocker arm 20a: Blank processed product (plate-shaped processed product) 20b: Bent processed product 22: Both side walls 30: One end connecting wall 30a: Corresponding area 40: Valve stem guide groove 41: Guide wall 41a: Protrusions 45 … Pressing groove 45a… Side 45b… Bottom

Claims (3)

[Claims] 1. An end connection wall, comprising: a pair of both side walls; and one end connection wall configured to connect between one end portions of the both side walls and to be in contact with a lower end of a valve stem tip. On both sides of the one end connecting wall, a pressing process is performed from the upper surface side, and a pair of convex ridges are formed on both lower surface sides of the one end connecting wall so as to protrude downward, between the pair of convex ridges. A rocker arm formed with a valve stem guide groove having a guide wall as a guide wall. 2. A step of obtaining a metal plate-like processed product having a predetermined shape, bending the plate-like processed product to connect a pair of both side walls and one end of the both side walls, And obtaining a bent product having an end connecting wall configured so that the tip of the valve stem abuts on the lower surface side, wherein the bending process is performed before the bending process is performed. On both sides of a region corresponding to the one end connecting wall in the plate-like processed product, a pressing process is performed from an upper surface side, and a pair of convex ridges are formed in a downwardly projecting shape on both lower surface sides of the corresponding region. Between the pair of ridges,
A method for manufacturing a rocker arm, comprising forming a valve stem guide groove having the convex portion as a guide wall. 3. The bent product is formed by bending the plate-shaped product by using a pressing groove provided on an upper surface side of the plate-shaped product as a bent portion, while forming the bent product. 3. The method of manufacturing a rocker arm according to claim 2, wherein one side surface of the pressing groove is brought into close contact with a bottom surface of the pressing groove by pressing both side walls of the article toward the one end connecting wall side.